One of the more important aspects of laying a good pipeline is the obtaining of a strong and durable coupling between the lengths of pipe, and, where necessary, providing a watertight seal to prevent any leakage therethrough. In addition, such a coupling should be as economical as possible, both in construction and in time of installation. The devices currently used for joining two lengths of pipe are called band or split band couplers and generally consist of large band or semicircular band sections (split bands) which are wrapped about the juncture of the adjacent pipe lengths, overlapping a portion of each pipe, and a pair of somewhat large brackets, one being secured to each end of the band or bands. Each bracket has one or more apertures therein for receiving bolt means which extend through the apertures and across the open ends of the band. Upon tightening, the bolt means draws the ends of the band together thereby coupling the pipe lengths.
While these couplers have been widely used for years on corrugated pipe, applicant has recently developed a channeled band coupler which has several advantages over the conventional band or split coupler. The channeled band coupler has a walled channel therein which fits about radial end flanges formed at the ends of the pipe lengths. The use of a channeled band coupler disposed about the abutting or adjacent flanges not only provides a stronger coupling in that it does not rely solely on radial pressure for its holding force, but is also considerably easier to use in the field and therefore more economical.
In joining lengths of pipe, the pipes must be properly aligned prior to coupling to prevent any leakage through the band. Split band couplers are of little assistance in obtaining a proper alignment. Pipe alignment is greatly facilitated by the channeled band coupler with its use of radial end flanges to secure the pipe length as such flanges are self aligning within the channeled couplers. It is also difficult to obtain a watertight seal using the conventional band couplers as the necessary gaskets are quite difficult to hold in place about the juncture of the pipe lengths. This problem is also alleviated by the use of the channeled band coupler as the walled channel is an ideal means for securing a gasket about the abutting pipe ends.
As indicated, the use of the channeled band coupler requires that the pipe lengths be provided with radial end flanges prior to coupling. Accordingly, it may often be necessary to maintain different types of coupling devices for use with flanged or non-flanged pipe. While channeled band couplers can only be used if the pipe lengths are provided with radial end flanges, band couplers can be used to secure lengths of flanged pipe, however, the strength of such a coupling is reduced due to the loss of surface area contact between the bands and pipe lengths caused by the formation of the radial end flange. Not only are the ends of the pipe lengths from which the flanges are formed removed from mating contact with the band coupler but the area on the pipe lengths adjacent the flanges are generally flatened out during the flange forming process for about one to two inches into a non-corrugated surface of generally constant radius which is also removed from contact with the band. The result is a loss of coupling strength when a band coupler is used to secure lengths of flanged pipe. It would be highly desirable to have a single coupling device which retained the benefits of the channel band coupler when used with flanged pipe but which would also provide a strong and durable coupling when used in securing non-flanged pipe.